Complex Traits

Genotype Codes for Dog Hair

ProcedurePart 2: Hair Genotypes

1. Remind students about what they already have learned about the gene mutation that determines whether a dog has long or short hair. (If necessary, revisit Slide 24.) Discuss the other characteristics that contribute to hair type in dogs. Show Slide 29 and explain that three genes govern the hair type in most breeds of dogs. The gene for hair length is one of the three genes. Curl is affected by a gene that codes for one of the structural proteins in hair. Like the gene for hair length, a single point mutation is responsible for the curly allele. In this case, however, one inherited copy of the mutation (Cc) causes soft, wavy hair and two copies (CC) cause soft, curly hair. A dog must have two copies of the original (“ancestral”) version of the allele (cc) to have straight hair.